Diagnostic strategy and risk assessment framework for complex chemical mixtures

Environmental contamination comprises a complex mixture of both organic and inorganic contaminants. Understanding their distribution, behaviour and chemical interactions provides the evidence necessary to make informed... [ view full abstract ]

Environmental contamination comprises a complex mixture of both organic and inorganic contaminants. Understanding their distribution, behaviour and chemical interactions provides the evidence necessary to make informed decision and implement robust remediation strategies. The current regulatory regimes use risk assessment to guide management strategies; however partitioning and bioavailability of chemical mixtures are rarely included. This inability contributes to an overestimation for risk estimation and risk characterisation. In order to address the issues of partitioning and bioavailability and therefore have a more rationale understanding of the factors that drive uncertainty in determining bioavailability, a series of soil mesocosms was setup. The three soils tested contained heavy metals and hydrocarbons and one of them was treated using physicochemical stabilisation. A sequential cylcodextrin and solvent extraction was used to determine the bioaccessible and total extractable fractions of hydrocarbons and chemometric identification of substrates and elements distribution (CISED) was used to measure the metal trace elements in soils. We are currently completing the analysis to describe the interaction of poorly biodegradable contaminants with particulate matter through its exchangeable and bound residues under the range of environmental conditions tested. The challenge is to develop standardised methods to assess dissolved-sorbed phases interactions of poorly water-soluble substances at the same time as assessing degradation of the bioavailable fraction.